Remapped - Now i want more boost!

[Stanley]

I may be being daft here, but hear me out.

I had my AGU engined A3 remapped a few months ago and it goes well.

Now, i suspect it is a very rich map as:

A: Its more safe and has less chance of a comeback on the chap who chipped it with it being a 'generic' map.
B: My MPG is alot worse even under normal driving conditions (I have serviced the car since and fitted uprated plugs)

I want to fit a boost guage to see what it is boosting to.

Once i have done this i want to tweak another couple PSI out of it.

Whats the best way of doing this?

Manual boost controller?
N75H?

Any other methods?

Cheers all!

 

[harryc]

Who did the map? Do you have an egt or wideband so you could monitor the effects of raising the boost?

 

[Stanley]

A local chip tuner. No RR or anything. Feels alot faster however which i guess is a success......

I have neither but suspect a wideband would be a good idea....

 

[Prawn]

Most stage 1 maps on the AGU pretty much max out the turbo anyway mate. Chances are you'll see very little gain from anything you do to it really, aside from changing the turbo!

Best bet is to get it running 100% as it is. it'll almost certainly have a boost leak from the PCV system under the inlet mani which will be costing you power!

 

[Stanley]

it'll almost certainly have a boost leak from the PCV system under the inlet mani which will be costing you power!

Please elaborate....

 

[aragorn]

If its rich, theres power lost right there.

I'd be wanting someone who can do proper custom maps to log the car on a dyno and see where to go from there.

 

[Stanley]

Im planning a trip to the dyno soon so will have a look at whats what then.

Whats this PCV lark? As per, its an abbreviation that i have no idea what it means.

 

[harryc]

Positive Crankcase Ventilation

 

[Prawn]

basically, it's a system that uses the vacuum in the inlet manifold at idle to draw gasses out of the crank case, then, under boost, there is a check valve to stop the boost going back down the system.

Sadly, on the AGU, the check valve is joined to the inlet manifold by a 6'' bit of pipe, with 2 90 degree bends in it.
It would appear, that the oilly vapour that is drawn through this tube eats the rubber over time, and they almost always split.

Since finding the fault on my old AGU about 2 years ago, I've only found one AGU that doesn't have a split, yet about 10 that do! So it's a fair guess to assume it'll be split on yours. it's almost always overlooked!

I fixed mine, and it made a huge difference, and my fuel economy went up massively too.

if it's leaking out under boost, the turbo will still be drawing the air in, so the MAF will see the high flows, and fuel for all that's been drawn in. If say 10% of that (for example) is then leaking out under pressure, you'll be having 10% too much fuel!

 

[Stanley]

Well I always say that every day is a schoolday! Thank you very much for the useful info! I will be sure to report back with my findings!

 

[aragorn]

thats not quite complete, because in the above scenario, the fuelling is monitored by the lambda sensor, which the ECU would be using to constantly attempt to adjust for the 10% overfuelling.

When the check valve is closed, the Pancake valve opens, and allows the crank case fumes to be drawn into the turbo inlet. The problem here is you've now also got unmetered air entering the system via the split, and the fuelling calcs get even further out of whack.

 

[Prawn]

does the system run in closed loop all the time once warmed up though? I was under the impression that it can go to open loop again under WOT in some circumstances, at which point it would only fuel from the MAF wouldn't it, and not take any data from the o2 sensor....

Good point about the TIP drawing in unmetered air through a split PCV though!

 

[aragorn]

Sort of.

WOT is open loop, but it includes the multiplicative and additive fuel trims.

So if normal driving has resulted in a +10% fuel trim, then that trim is still applied at full throttle, it just doesnt try to continue adjusting it.